This invention relates to electronic devices used in sporting-type games. More particularly, this invention relates to electronic devices used in baseball games.
In the game of baseball, incoming pitches are directed towards an imaginary strike zone that is adjacent to the batter's box where the batter stands. A pitched ball which passes through at least a portion of the strike zone is called a "strike", regardless of whether the batter swings the bat at the pitched ball. A batter is allowed a predetermined number of strikes before he is called "out". Any pitch that does not pass through a portion of the strike zone and is not swung at by the batter is called a "ball". If the batter receives a predetermined number of "balls", he progresses or "walks" to first base.
Although there are several definitions of the term "strike zone", for purposes of this application, a "strike zone" is an imaginary area that is located above the home plate. The strike zone is defined by right, left, upper and lower boundaries. The right and left boundaries are imaginary vertical planes that extend upward from the right and left sides of the home plate. The lengths of the vertical sides depend upon the height of the batter. In general, the upper boundary of the strike zone is a plane aligned with the armpits of the batter, and the bottom or lower boundary is a plane aligned with the knees of the batter. Since batters have different heights, it is apparent that the upper and lower boundaries of the strike zone vary from batter to batter.
A human umpire is typically required to determine whether the pitched balls are "balls" or "strikes". There are several disadvantages of having a human umpire calling balls and strikes. One disadvantage is the expense involved in paying the umpire to perform his duties. In not-for-profit baseball leagues, it is often difficult to adequately pay the umpires. Umpires must then be found to volunteer their time to umpire a baseball game. In some baseball leagues, for example, the expense of obtaining an umpire is prohibitive so that no umpire is used. In that event, the baseball teams are required to decide between themselves whether a particular pitch is a "ball" or a "strike". Disagreements as to the call of a particular pitch are inevitable in such cases.
Another disadvantage of using human umpires is that they make mistakes. No human umpire is capable of total accuracy in determining whether an incoming pitched ball passes through a portion of the strike zone. Also, there is a great deal of variation in the way different human umpires call balls and strikes. Some umpires use a so-called "small" strike zone because they tend to narrowly define the imaginary boundaries of the strike zone. Other umpires use a so-called "large" strike zone, or call pitches very erratically. In any case, it is apparent that there are many disadvantages whenever a human being must be used to call balls and strikes.
Several attempts have been made to devise electronic systems to avoid the need for human umpires. For example, U.S. Pat. No. 5,069,450 to Pyle is an automatic umpire for slow pitch softball which detects the impact of the pitch on a surface placed behind the baseball home plate. Any pitch which hits the surface is considered a "strike". The Pyle apparatus is obviously limited to use in slow pitch softball games in which the parties agree in advance that a strike is any pitch which hits the indicated surface.
U.S. Pat. No. 4,941,662 to DePerna discloses a sophisticated, electronic baseball game that includes a pitch detection mechanism. However, the pitch detection mechanism requires a pair of substantially spaced sensors, one near the playing surface and one on the ceiling. These and other sensors must be electrically connected together in an elaborate system to detect whether a pitched ball is within the strike zone. The system in DePerna is very complicated and expensive, and probably cost prohibitive for most applications.